Ab initio non-adiabatic coupling elements: the conical intersection between the 22A′ and the 32A′ of the H+H2 system

The conical intersections between the 12A′ and 22A′ electronic states and the 22A′ and 32A′ electronic states of the H2+H system were characterized by line-integral calculations using ab initio non-adiabatic coupling terms. The calculations confirmed that when a contour surrounds the {12A′,22A′} conical intersection but does not approach, too closely, the {22A′,32A′} conical intersections the line-integral produces for the topological phase, the expected π-value [Chem. Phys. Lett., 319 (2000) 489]. Estimating the location of {22A′,32A′} conical intersection, the line-integral procedure was employed again – this time for the {22A′,32A′} system – confirming, in the same way, also the existence of the {22A′,32A′} conical intersections.